Slide rule



2 Sheets-Sheet 1 in 2? 3m i W. ili! M 13 3 MM T w w a in n w WW m m m w m 6 1 ,m M m 5. w 2 5w w m a M m 2 a u g N F. DURAND SLIDE RULE 'h Td r m um mM m am July 29, 1958 Filed Dec. 26, 1956 July 29, 1958 F. DURAND suns RULE- Filed Dec. 26, 1956 2 sheets sheet 2 Patented July 29, 1958 2,845,225 SLIDE RULE Frangois' Durand, Le Vesinet, France Application December 26, 1956, Serial No. 630,649

Claims priority, application France December 29, 1955 6 Claims. (Cl. 23570) This invention relates to slide rules and its essential object is to provide an improved slide rule having a run ner associated with coupling means wherebyirrespective of its position along the slide rule-4t can be coupled with the intermediate movable slide carrying the multiplicand and dividend scales. The fixed-scale bars or members of this slide rule are provided at their ends with checks adapted to stop the runner in the position in which it covers one of the end lines of the bars carrying the fixed scales, i. e. the multiplying and dividing scales of the slide rule.

A slide rule of the improved type broadly set forth hereinabove incorporates many advantageous features in comparison with conventional slide rules since it is possible therewith to displace the runner bodily with the slide after the former has been placed beforehand in the preliminary position in view of performing an operation. Thus, the reading of the final result as well as the operations themselves are greatly facilitated.

The slide rule according to this invention is characterized essentially in that its runner consists of a pair of small plates disposed on either side of the rule and adapted to be slightly moved in relation to each other in the transverse direction, each of these small plates carrying on its inner face a suitably shaped rib or fin slidably engaging the longitudinal grooves or slits formed in the registering faces of the rule, the ribs of these small plates being adapted on the other hand to engage said slide in reverse directions to couple same with the runner when the small plates of the runner are slightly moved in opposite transverse directions with respect to each other and the runner itself is displaced along the rule, this relative transverse movement of the small plates being obtained by exerting with the fingers moderate pressures in opposite directions on the outer edges of these plates.

Thus, this particularly simple action enables the operator to drivingly connect the runner with the movable slide to move the latter bodily with the runner. When the opposed pressures exerted on the small plates of the runner are released, these plates resume their initial or normal positions under the influence of adequate spring means. Then the plates of the runner are guided during their sliding movement on the rule without carrying along the slide proper. i

According to a first embodiment of the improved slide rule of this invention the longitudinal grooves or slits adapted to be engaged by the ribs, fins or like projections of the aforesaid small plates of the runner are formed on either side of the slide proper, and consequently these ribs are formed on the inner face of each plate.

According to another embodiment of the invention the longitudinal grooves engageable by the aforesaid ribs consist of two grooves already provided between the slide and the fixed bars, but these grooves are somewhat widened and situated on opposite faces of the slide, adjacent the opposite edges thereof, whilst the ribs of the small plates are positioned accordingly and adapted to CTI clamp the opposite edges of the slide for efiiciently coupling the latter with the runner.

In order to afford a better understanding of the present invention and of the manner in which the same may be carried out in the practice, reference will now be made to the accompanying drawings forming part of this specification and illustrating diagrammatically, by way of example, two typical embodiments thereof. In the drawmgs:

Figure l is a plane view from above showing a first embodiment of the slide rule according to this invention.

Figure 2 is an elevational side view of the slide rule.

Figure 3 is another, fragmentary plane view from above showing on a larger scale the same slide rule, the runner being shown in longitudinal section taken upon the line IlI-III of Fig. 2.

Figure 4 is a cross-sectional view of the slide rule with its runner, the section being taken along the line IV'IV of Fig. 3.

Figure 5 is a view similar to Fig. 3 but shows the runner drivingly connected with the slide.

Figure 6 is a view similar to Fig. 4 and shows the runner drivingly connected with the slide.

Figure 7 is a plane view from above showing a modified embodiment of the slide rule according to this invention.

Figure 8 is a cross-sectional view showing on a larger scale the slide rule of Fig. 7; and

Figure 9 is a similar cross-section but showing the runner operatively connected with the slide.

The improved slide rule illustrated in Figs. 1 to 6 of the drawings consists in the conventional way of a pair of fixed bars 1, 2, a slide 3 being slidably mounted therebetween. This slide 3 has formed on each longitudinal edge a longitudinal rib 4 preferably symmetrical in relation to the median plane of symmetry of the slide. This rib engages a guideway in the form of a groove formed in the edge of the relevant fixed bar. The two fixed bars 1, 2 are assembled at their ends by cross-bars 5, 6 the latter also acting as stop members to the runner. The runner consists of a pair of small plates 7, 8 disposed on either sides of the bars 1, 2 and interconnected at their upper and lower edges through means whereby these plates may be moved to a limited extent in rela tion to each other by exerting opposite pressures in directions substantially parallel to their planes. Both small plates 7, 8 are formed on their inner faces with ribs or like projections 14a, 15a adapted to ensure the desired driving connection between the runner and the slide as will be made clear presently. The longitudinal guide grooves 17a, 18a for receiving the ribs 14a, 15a of the small plates 7, 8 are formed in the opposite sides of the slide 3 and preferably in the vicinity of the median axis thereof. The ribs 14a, 15a are formed accordingly on the inner faces of the plates 7, 8. The grooves 17a, 18a are slightly wider than the ribs 14a, 15a to permit a moderate transverse movement of the plates 7, 8 in opposite transverse directions.

Along its edges 7a, 7b parallel to the fixed bars 1, 2 the plate 7 carries a key-like projection 22a or 22b extending at right angles to the main plane of the plate 7 and parallel to the relevant edge of the slide rule. The projection 22a is provided with a mortise and the other projection 22b is of tenon configuration. Similarly, the other plate 8 has formed along its upper and lower edges a pair of key-like projections 23a, 23b, but in this case thearrangement is the reverse in that the projection 23a is of a tenon configuration and engages a mortise formed in the projection 22a of plate 7. Finally, the other projection 23b has a mortise formed therein and receives the tenon forming the projection 22b of plate 7. Thus, the interfitting pairs of tenons and mortises will permit the assembling of the two small plates 7,,8 while allowing the freedom of movement required for their relative transverse displacement in opposite directions. Moreover, this interfitting arrangement will guide the plates during their. relative movements.

The ends 22d of the mortise carrying projection are thicker than and project from the inner. face of the projection to engage. the correspondingedge. of the'slide rule. The. same applies on the other side tothe. ends 23d of the mortise-carrying projection 23b. When these thicker end portions 22d or 23d of the mortise-carrying projections engage the edges of the slide rule the two ribs 14a, 15a are positioned by construction in the middle of the guide grooves 17 a, 18a so that they do not contact the upper and lower walls thereof. On the other hand, the depth of these ribs 14a, 15a is calculated to prevent them from contacting the bottom walls of the grooves 172:, 18a. Thus, in the inoperative or uncoupled positionshown. in Figs. 3 and 4 the ribs 14a, 15a do not contact the. slide Sand the latter cannot be carried. along by the running during. its longitudinal movements along the. slide rule.

The small plates 7, 8 are held in this position by suitably shaped leaf springs 24a, 24b. The spring 24a. urges the tenon-shaped projection 23a of plate 8 in the direction of the arrow f thereby pressing the thicker ends 23d of its opposite mortise-carrying projection 23b against the registering edges of the slide rule. Similarly, the spring 24b urges the tenon-shaped portion 22b of plate-7 in. the direction of the arrow f thereby pressing the thicker ends-22d of its opposite. projection 22a against the other edge of the slide rule. Each spring is adapted to' react with its end portions against the corresponding edges: of the slide rule, as shown. Besides,.these springs 24a, 24bare housed in the free space available between the thicker end'portions 22d, 23d of the mortise-carrying: projections 22a, 2312 respectively.

Figures 3 and 4 of the attached drawings illustrate the component elements of the runner in their normal positionsas described hereinabove. ln this position it ispossible to move the runner along the slide rule without carrying along the slide 3 since the ribs 14a and 15a. are

located in the middle of the grooves 17a, 18a and do not contact the walls thereof. Thus, the runner is guided with all the desired efficiency and accuracy during its movements, due to the sliding engagement provided between the thicker ends 22d, 23d of the mortise-carrying projections 22a, 23b and therelevant edges of the slide rule.

When it is desired to drivingly connect or couple the runner with the slide 3 this may be obtained by simply exerting with the fingers two pressures of opposite directions as illustrated by the arrows F F against the upper and lower edges 8a, 7b respectively of the plates 8, 7 (Figs. 5 and 6). In fact, the pressure exerted in the direction of the arr-ow F on the edge 7b of plate 7 will press the rib 14a against the opposite wall of the groove 17a of slide 3. Similarly, the pressure exerted in the direction F on. the edge 8a of plate 8 will press the rib a against the opposite wall of the groove 18a. As a result, a wedging action takes place between the ribs and the slide 3 and the latter is drivingly connected with the runner. Consequently, under these conditions the slide 3 may be moved bodily with the runner, provided of course that the pressures F F are maintained. At the same time, the slight transverse relative displacement of the plates 7, 8 in opposite directions has caused the tenon-shaped projections 23a, 22b to move somewhat out from the mortisecarrying projections 22a, 2312, as the springs 24a, 24b are flattened.

Figures 7 to Q of the drawings illustrate another typical embodiment of the slide rule of this invention. This modified embodiment is based on the same principle as the preceding embodiment but in this case no groovesare formed in. the slide 3. The ribs. or fins 1.4, 15 of plates 7, 8:engage:a pair of grooves. formedzby widenedportions;

4 of the intervals provided beforehand between the fixed bars 1 and 2, and the movable slide 3.

More particularly, the ribs 14 of plate 7 engage the groove 16 formed by a widened portion of the interval between the fixed bar 1 and the slide 3, said widened portion being provided on the side. of plate 7. The ribs 15 of plate 8 engage the groove 17 positioned on the other face of the slide rule and symmetrically to the groove 16 with respect to the longitudinal median line of the slide rule. This groove 17 consists of a widened portion of the interval formed. between the bar 2 and the movable slide 3, this widened portion being provided on the side of the plate 8. Thus, the ribs 14, 15 are located on either sides of the slide 3.

The plates 7, 8 are interconnected along their corresponding edges by resilient strips 9, 10 engaging the registering edges of the slide rule so that these strips urge the plates 7, f the runner in the direction of the arrows f and f respectively.

Thus, the ribs 14 of plate 7 are pressed against the fixed bar 1 and the ribs 15 of plate 8'- are pressed against the fixed bar 2 (see. Fig. 8). Consequently, the runner may be moved along the rule without carrying along the slide 3-. Moreover, the runner is properly guided along the slide rule by the engagement between the ribs 14, 15 and bars 1, Zrespectively.

The driving connection between the runner and the slide 3 may be obtained by simply exerting; a moderate pressure in opposite directions, as indicated by the arrows F F against the edge 7b of plate 7 and against the edge 8a of plate 8' respectively, these opposite pressures producing a moderaterelative displacement ofboth plates until the ribs 14' of plate 7 and ribs 15 of plate 8 engage the corresponding edges of the slide 3 (Fig. 9). Thus, the. slide is somewhat" clamped between the ribs 14, 15 and drivingly connected with the runner. As a consequence, therunner may be moved bodily with the slide, but when the aforesaid pressures F and F; are released, the resilient strips 9, 10 will immediately restore the plates 7, 8- to their initial positions in which they permit the movements of the slide independently of the runner.

The slide rule according to this invention is particularlyadvantageous since the operator may, by performing a very simple movement, couple the runner with the middle slide so as to displace them bodily, thereby simplifying considerably the problems to be performed therewith.

What I claim is: I

1 Slide rule comprising two fixed bars rigid with each other, a movable slide slidably mounted between said bars, a pair of plates disposed on either sides of the slide rule and constituting the runner thereof, assembling means between said plates for fastening the latter in the longitudinal direction while permitting a limited relative movement thereof in the transverse direction, at least two longitudinal guide grooves in the slide rule, at least one side wall of each groove being formed on the movable slide, one of said grooves being formed on one face of the slide rule and the other groove on the other face, ribs rigid with the inner faces of said plates and projecting into said groove, resilient means bearing on said fixed bars and urging'said plates, whereby the" ribs of said plate will not contact the walls of said movable slide when said plates are not moved in the transverse direction.

2. Slide rule according to claim 1, wherein said plateurging resilent means consist of a pair of curved metal strips mounted along the edges of said fixed bars and bearingthereon to urge said plate.

3. Slide rule according to claim 1, wherein said longitudinal guide grooves are formed in one face of said movable slide and in the other face ofsaid' movable slide.

4. Slide rule according to claim 1, wherein each plate of said runnercomprises on an edge. parallel to the slide rule a tenon projecting at right angles to the general plane of the rule and on the opposite edge another projection formed with a mortise corresponding in shape to said tenon, said tenon and mortise arrangement of one plate being reversed on the other plate, the tenon of each plate engaging the mortise in the projection of the other plate.

5. Slide rule according to claim 4, wherein the projection perpendicular to each plate and wherein a mortise is formed comprises at either ends an inwardly-projecting extension adapted in the inoperative condition to engage the edge of the relevant fixed bar of the slide rule, the length of said extensions being calculated to prevent said plate ribs from contacting the movable slide.

6. Slide rule according to claim 1, wherein said two longitudinal guide grooves consist of two widened portions of the intervals provided beforehand between the fixed bars and the movable slide, said guide grooves 5 being located on opposite faces and in the vicinity of longitudinal opposite edges of the slide rule.

. References Cited in the file of this patent UNITED STATES PATENTS 1,461,975 Eaton et al July 17, 1923 FOREIGN PATENTS 400,850 Germany Aug. 23, 1924 

